Seed filling performance of dual-purpose seed plate in metering device for both rapeseed & wheat seed

Abstract: In view of the differences of the physical and mechanical properties between rapeseed and wheat seed, a dual-purpose pneumatic precision metering device within the internal guiding strips fixed on the seed plate for both rapeseed and wheat seed was developed in this paper. Its working principle and the whole structure of the dual-purpose pneumatic precision metering device were expounded. The mechanical model for the single rapeseed or wheat seed on the compulsive driving layer in the filling area was established via the analysis of the motion trajectory of each single seed: rapeseed or wheat seed which was from the compulsive driving layer on the internal guiding strip, the filling angle of the seeds in filling area and the flowing characteristics of both rapeseed and wheat seed on the layers in the filling area were analyzed with the help of high-speed camera technology. The tests for the performance of seeds filling and the experiments of how the filling angle of rapeseed or wheat seed in the filling area changed, and the tests of the dual-purpose pneumatic precision metering device of its mechanical damage to seeds when the dual-purpose pneumatic precision metering device was working within the internal guiding strip fixed on the seed plate were carried out one by one. The results of the tests for the dual-purpose pneumatic precision metering device showed that: while the rotating speed of the seed plate inside the dual-purpose pneumatic precision metering device was 10-45 r/min, the seeds filling angle and the rotating speed had a linear correlation, the rapeseed and wheat seed filling angle obtained a value ratio of 1.6635 and 1.9929 with the changing of rotating speed when the internal guiding strip was fixed on the seed plate and the filling angle of rapeseed and wheat seed respectively got average increment of 10.1° and 13.45°, the seeds filling arc length average increment respectively were 12.29 mm and 16.48 mm, compared to the seed filling angles when the internal guiding strip was not fixed on the seed plate. It indicated that the performance of the dual-purpose pneumatic precision metering device for both rapeseed and wheat seed of seed filling using the internal guiding strip fixed on the seed plate improved conspicuously. The germination rate for the rapeseed and wheat seed tests showed that there was no mechanical damage to the seeds when the internal guiding strip was fixed on the seed plate. The test results of seeding performance of the dual-purpose pneumatic precision metering device showed that: when the negative pressure was -2 900 Pa, the average qualified index of the wheat seed was relatively increased by 30.76% and the missing index was decreased by 38.61% within the internal guide strip fixed on the seed plate while the dual-purpose pneumatic precision metering device was working. When the negative pressure was -900 Pa and the positive pressure was 500 Pa, the seed average qualified index was relatively increased by 3.72%, and the missing index was decreased by 8.58% within the internal guide strip fixed on the seed plate, while the dual-purpose pneumatic precision metering device was working. While the rotating speed of seed plate inside the dual-purpose pneumatic precision metering device was 20-30 r/min, the seeding performance of the dual-purpose pneumatic precision metering device could meet the requirements for sowing for wheat seed and rapeseed. This research can supply the study basis to structure improvement and performance optimization of dual-purpose precision metering device.